The present invention relates to integrated circuits (ICs), and more particularly to generating reference clock signals within ICs.
Crystal oscillator circuits are used in a variety of digital and analog circuit applications. In particular, analog circuit applications of crystal oscillators include communication systems which use a sinusoidal (or sine wave) output signal from a crystal oscillator. In some communication systems the crystal oscillator may be tunable in frequency. At the selected frequency, the sine wave signal produced by the crystal oscillator is ideally represented in the frequency domain by only the desired frequency component. Any frequency components present in the crystal oscillator's output signal other than the selected frequency, are considered harmonics and can cause problems in the system.